1. Field of the Invention
The present invention relates to a technique of semiconductor, and especially to a constant current semiconductor device having a Schottky Barrier made by using the principle of metal/semiconductor contacting, the structure/characteristic of the constant semiconductor is different from that of a Schottky diode.
2. Description of the Prior Art
A PN diode made of semiconductor basic material is formed according to a basic principle of combining a P type and an N type semiconductor basic material by a semiconductor diffusing technique etc. and then packing the combined semiconductor basic materials, and having an external circuit connected with electrodes. More often seen case in using is taking advantage of the character that electric current is easier to flow from the P type are to the N type area but less easier to flow in a contrary direction, in order to get a rectifier for use. And more, a Schottky diode is used for electric rectifying by taking advantage that a Schottky Barrier made by metal/semiconductor combining can also have the character of letting passing of electric current in one way and not allowing passing of electric current in the other way. Particularly, the PN diode/the Schottky diode are used in rectifying an alternate circuit power source into a direct circuit power source, to be provided for using by electronic circuits of a normal electric product.
Except that the above PN diode/Schottky diode can be used as rectifiers, according to different functions and material characters of various diodes, the diodes can include Zener diodes, switching diodes, photo diodes etc. Further, an LED (light emitting diode) having the characters of saving energy, being light, thin and small had been widely used on various electronic products since a very long time ago. After development of the technique of hi-brightness LEDs, the LEDs show their ability of taking the places of the conventional illuminative light emitting devices such as in those devices for industrial use, house illumination, traffic road use etc., we can see LEDs in use.
For the above mentioned LEDs and general electric circuit designing, we often see constant voltage power source for which LEDs' arrays are used, so long the output voltage of the circuit of the power source meets the rated voltage of the LED array, the LED array can be driven. However, various LED arrays can be of different amount and of different voltage values being due to different places they are used in, outputting of overly high voltage to the circuit of the power source must be limited according to the amount of the LEDs and their matched series current limiting resistances, this will induce power loss; moreover, when part of the LEDs in the LED arrays are damaged, the entire voltage will be lowered, electric current will be increased to render other LEDs to be damaged one by one; additionally, the constant voltage power source may frequently have the problem of twinkling in use because of the unstable voltage.
In order to overcome the above problem, theoretically, to adapt a constant current power source control mode will be better than a constant voltage power source control mode, however, the constant current power source control mode practiced presently uses the devices composed of complicated composited integrated circuits of very high cost; if the devices are made in a mode of using bipolar constant current and taking a plane technique of complicated PN interface transistors, not only their rate of superiorities are bad to render impossible of mass production, but also larger driving electric currents are not easy to be created.
In view of these, the inventor of the present invention provided a constant current semiconductor device having a Schottky Barrier to eliminate the defects of the prior techniques after having studied and having practical experience in the technical field of semiconductor for years.